For testing fluid pumps, especially high-pressure fuel pumps, and fluid injectors (fuel injectors) in a test stand, the fluid used for the testing (test oil) should have a defined temperature. Depending on the prevailing ambient and operating conditions, this requires that the employed fluid be heated or cooled.
Conventionally, the fluid removed from a tank is routed through a heat exchanger in order to cool it prior to conveying it to the fluid pump.
In addition, a heater is frequently provided in the fluid tank so as to heat the fluid, if necessary.